Quick Selection Tool - Cut to layer issue

[hba]

Hi,

I'm using Photoshop cs5. I'm playing around with a painting I downloaded of the web (jpg). I'm used the quick selection tool to select an area of the painting then I go to new layer 'layer via cut'. Then what I get is a gray line where the selection border was...

This doesn't happen when I use other selection tools. I was wondering what am I doing wrong?

Thank in advance!

[RdG]

I try to reply to you, when you using a quick selection tool, did you chos the anti-alia option on the options bar?